from collections import defaultdict
pd = (2,3,5,7,11,13)
cd = (4,6,8,9,10,12)
def func(dp,D):
	t_dp = defaultdict(int)
	for k,v in dp.iteritems():
		for d in D:
			t_dp[k*d] += v
	return t_dp
P,C = map(int,raw_input().split())
dp = {1:1}
for i in range(max(P,C)):
	if i < P:
		dp = func(dp,pd)
	if i < C:
		dp = func(dp,cd)
print sum(k*v for k,v in dp.iteritems())/(6.**(P+C))